1. Field of the Invention
The present invention relates to a method of introducing a casting compound composed of aggregates and a matrix with a hardening binder into a hollow space within a tubular sheathing of a tension member composed of one or more individual elements, particularly in the anchoring range of the tension member relative to a structural component. In accordance with the method, the aggregates are introduced first and the matrix is then introduced in the liquid state into the grain structure formed by the aggregates.
2. Description of the Related Art
In corrosion-protected tension members, for example, prestessing members for prestressed concrete or stay cables for cable-stayed bridges, frequently several individual elements, such as, steel rods, steel wires or steel wire strands, are combined into a bundle and are arranged within a tubular sheathing. In the area of the free length of the tension member, this tubular sheathing usually is composed of a sheathing tube of synthetic material, for example, polyethylene. In the anchoring range where the individual elements are spread apart for anchoring, the tubular sheathing is composed of an outwardly flaring steel pipe. In order to protect the individual elements within the tubular sheathing against corrosion, on the one hand, and to achieve a bonding action between the individual elements and the tubular sheathing where the tubular sheathing is of steel, for example, in the anchoring range, on the other hand, the hollow space remaining between the individual elements and the tubular sheathing is filled out with a casting compound of aggregates and a matrix with a hardening binder. This casting compound is usually a cement mortar which is injected into the hollow space by means of appropriate injecting lines.
In a stay cable for a cable-stayed bridge which is loaded by a permanent load, i.e., dead weight, as well as by changing loads, i.e., traffic loads, it is also known to separate the introduction of the traffic loads into the structure from the introduction of the permanent loads. In that case, the permanent loads are introduced into the structure through the individual anchoring points of the individual elements. For introducing the traffic loads which occur only after tensioning and injection of the casting compound, a bonding action is produced in the anchoring range between the individual elements and a steel pipe which forms the tubular sheathing in this range, so that the traffic loads are introduced into the steel pipe by the bonding action of the individual elements and the traffic loads are introduced directly from the steel pipe to the concrete of the structure, as disclosed in German patent 21 14 863. This means that the actual anchoring points of the individual elements remain essentially free of the vibratory stresses due to traffic loads.
For anchoring the tension members within the hollow space of a support body, for example, an anchoring sleeve, particularly for anchoring wire bundles which are spread apart in the manner of a broom for anchoring, a casting compound of grains and hardening binder is known from German patent 16 09 722. Within this casting compound a tightly packed heap of metal grains forms support vaults between the inner surface of the support body and the tension members, while the binder is introduced in the liquid state into the hollow space only after the metal grains have been filled into the hollow space. Initially, the hollow space is filled from the top with metal grains up to a certain level and the filling is treated in such a way that the grains are tightly packed. Subsequently, the binder is pressed in from below through an inlet opening, so that the binder fills out all hollow spaces between the metal grains and the wires embedded in the metal grains. The binders may be reaction-hardening synthetic materials or also an inorganic binder, namely, cement suspension. Because of the high costs for the metal grains, such a casting compound is only suitable, if at all, for anchoring systems which are prefabricated in a factory.